THE MATING of the clam shrimp
is a joyous ballet to our eyes, yet
it is actually a dance of death.
Their little rock-pool home has
shrunk steadily during days of un
relenting sunshine. Since early this
September morning, Bob Sisson, Lew
Nielsen, and I have kept watch beside
the diminishing water. Before the sun
sets, we calculate, the last of it will
evaporate. For the little pool's thou
sands, this is doomsday.
By 10:30 a.m., as the heat mounts,
the pothole's populace shows agitation.
Snails burrow into sand, where they
have hope of surviving while the damp
ness lasts. Tadpole shrimp wallow
downward into the bottom mud, as if
in retreat from the pool's lowering sur
face. In the shallow fringes fairy shrimp
by the hundreds flail and writhe, their
wet bodies reflecting dancing bits of
sunlight. Marooned by retreating water,
they can only die, together with myriads
of speck-size seed shrimp, copepods,
and other tiny crustaceans.
In the narrowing, warming pool the
clam shrimp-up to now given to only
occasional mating-become possessed
by the drive to reproduce. A score or so
of pairs, most of the clam shrimp popu
lace, swim locked in a T embrace, the
male grasping the belly of the female,
whose translucent form bares orange
masses of eggs (right).
They weave a giddy course of dives
and soaring climbs, turns and glides,
impeded now and then by lone males
trying to cut in. At last they part, the
male to burrow into the sand, the fe
male following after a moment's rest.
Next day we return to find only
damp sand in the pothole. So fragile
are all its tiny dead creatures that we
are hard put to discover a carcass in
tact. Sun and wind have already dried
and crumbled the tiny victims.
But in the sand the snails still live,
and in thousands of eggs and in the
gnats' pupae and larvae, the seeds of a
new generation await only the coming
of rain. Then the hole will fill once
more, the water will warm, and the
sparkling pool will teem again with the
vigor of the life force as on the first day
of the world.
[
National Geographic, October 1975
578